bugfixes and updated go.mod

vendor/github.com/RoaringBitmap/roaring/roaring.go

@@ -364,17 +364,20 @@ func (rb *Bitmap) String() string {
 	return buffer.String()
 }
 
-// Iterator creates a new IntIterable to iterate over the integers contained in the bitmap, in sorted order
+// Iterator creates a new IntIterable to iterate over the integers contained in the bitmap, in sorted order;
+// the iterator becomes invalid if the bitmap is modified (e.g., with Add or Remove).
 func (rb *Bitmap) Iterator() IntIterable {
 	return newIntIterator(rb)
 }
 
-// ReverseIterator creates a new IntIterable to iterate over the integers contained in the bitmap, in sorted order
+// ReverseIterator creates a new IntIterable to iterate over the integers contained in the bitmap, in sorted order;
+// the iterator becomes invalid if the bitmap is modified (e.g., with Add or Remove).
 func (rb *Bitmap) ReverseIterator() IntIterable {
 	return newIntReverseIterator(rb)
 }
 
-// ManyIterator creates a new ManyIntIterable to iterate over the integers contained in the bitmap, in sorted order
+// ManyIterator creates a new ManyIntIterable to iterate over the integers contained in the bitmap, in sorted order;
+// the iterator becomes invalid if the bitmap is modified (e.g., with Add or Remove).
 func (rb *Bitmap) ManyIterator() ManyIntIterable {
 	return newManyIntIterator(rb)
 }
@@ -418,6 +421,7 @@ func (rb *Bitmap) Equals(o interface{}) bool {
 	return false
 }
 
+// AddOffset adds the value 'offset' to each and every value in a bitmap, generating a new bitmap in the process
 func AddOffset(x *Bitmap, offset uint32) (answer *Bitmap) {
 	containerOffset := highbits(offset)
 	inOffset := lowbits(offset)